Mercury switch



Dec. 7, 1937. U. c. HEDIN ErAL n MERCURY SWITCH Filed June 10, 1935- (Patented Dec. 7, 1937 f UNirsD STATES PATENT- OFFICE I zusam. Y

'Uno C.

tionof Illinois neaimimrcalriu.Linton,lilium-erna.,

toTheAdlakeOompannImapplication 1m 1o, 1935, No. assis The Durvole of this invention is to increasethe current lcarrying capacity. o flmercury switches; i to permit higher Avoltages to be used; to protect against'switch failure by increasing the factor I 'of safety; land to achieve all of vthese advantages without materially increasing thel cost of manufacture and without complicating to any appreciable extent the processes of fabrication.

Further and other objects and advantages will l' become apparent as the disclosure proceeds and the description is read in conjunction with the accompanying drawing, in which Fig. l is a sectional view showing a magnetically controlled merciu'y-displacement switch made in 1 5 accordance with this invention; i

Fig.) is a cro sectional view through the disthe view being taken on the line 2-2 of 1"!8. g

"1lig. 3 is afragmentary, perspective view lshowa ing a form` of the invention that is preferred for v some installations;

Figs. 4 8 inclusive are fragmentary views show-g,

i I i118 further modifications of the, invention.

. Itwill be understood that the several embodiments of the invention shown in the drawing and .hereinafter described have been selected for the purpose of and the appended claims arenottobe construedaslimitedtothese specific u -forms, or any of them, unless required'by the )Ill prior art. Also, it will be understood that .various changes can be made in the forms disclosed without departing from the spirit of the invention.-

The invention is particularly applicable to switches of the type disclosed in Irson Patent l l No. 1,987,247 in which a magnetically controlledplunger or displacer is vertically reciprocable within a hermetically sealed switch' envelope havlng amercurynll that is'ada'ptedtoopenorclose the circuit through spacedelectrodes in the en- 40 velope according to the position of the displacer withlntheenvelope.

It is customary in this typeof switch to have one electrode continuously. in contact with the" mercury and another projecting upwardly through i the mercury but insulated therefrom (when the switch is in oif position) by a glass sleeve fused on the electrode. i v

. There is always a possibility in a switch of. this type that the insulating ,sleeve surrounding the' one electrode may crack, or k, in which case the circuit through the switch would be perma- It is one of the purposes of this invention to. insure against this possibility Referring now to the drawing, and particularly 55 to l, a switch envelope is indicated at Il,

12 claim. (ci. zoo- 112) .which may be of glass, or other mutable materiel.

.having a pair of electrodes I I and l2, preferably of tungsten or molybdenum, which are pinchsealed through thebase of the envelope as indicated at Il. Each electrode has fused to it a glass .5 insulating sleeve I4 which extends from the pinch seal il of the envelope to a point I5 adjacent to the tops of the electrodes. In the embodiment of the invention shown .in Figs. l: and 2,'the bared ends i6 and I1 of the electrodes Il and I2, re- 10 'spectively,' are bent over the insulating sleeve I4 in opposite directions and in order to save space, the bared ends may be twisted to an' acute angle with respect to the vertical plane through the A mercury fill i8 occupies the lower part of the switch envelope and normally has its level below the bent-over ends I6 and I7 of the two electrodes. The mercury level, however, may be shifted by energizing a coil I l associatedy with the switch which causes a displacer, generally designated 20, composed in part of magnetic material, to move downwardly within the envelope and displace a su'icient quantity of mercury to bridge the overhanging tips of the electrodes i I and i2, thus closing the circuit through the two electrodes. When the coil is de-energized, the displacer rises by buoyancy to the position shown in Fig. 1 and the circuit through the electrodes is broken.

The displacer may be of any suitablefor'm but 30 is here shown as consisting of a sleeve 2|y surmounting a glass sleeve eMythe two parts being held in xed relative position by coil springs 23, preferably of tungsten or molybdenum, which frictionalLv engage the projecting ends of the Blass tube 22 andY clamp hardened guide washers 2l of tool steel in place. The springs serve the double function of holding the component parts of the switch together and protecting the switch envelope from damage during-shipment.

The coil Il has an iron circuit associated with it which is substantially the same as that shown in` Larson Patent No. 1,967,247 and no further Vdescription is deemed Vnecessary here. A

Oneof the particular advantages of this switch over that disclosed in Larson Patent No. 1,987,247

is that double protection is aifoded against the possibility of switch failure due to therackins of the insulating sleeve surrounding the electrodes. For example, should the insulating sleeve 5U `|4 around one of the electrodes crachthe switch would not be short circuitedV because the other insulating sleeve would separate the electrodes i and i2. 'l

t Anotherinhereut ad tage is that higher voltages can be used due tothe increased dielectric strength separating the electrodes. Furthermore, higher currentscan be carried with a switch made in accordance with this -invention due to the fact that .only a small quantity of mercury lis used to bridge the gap between the two electrodes with the result that the heating effect of the current through the mercury is confined to an area that' is small in comparison with the entire mercury ll.

The modied form of the invention shown in `Fig. 3 is used where the switch ,is to carry `exceptionally high voltages. The only diil'erence between the form of the' invention shown in Figs. 1v and 2 and thatshown in Fig. 3 is that in the former, the bent-over ends I8 and I1 of thev electrodes I I and I2 lie in planes making an acute angle with respect to the vertical plane through the sleeves I4, while in the later, the bent-over ends lie in parallel planes that are at right angles to the plane through the sleeves I4. This latter arrangement has the advantage that there is a greater air gap between the exposed portions of the electrodes, and the switch has acorre spondingly greater voltage capacity. It has,

however, the disadvantage that the overall dil mension of the switch must be somewhat larger in order to permit the ldisplacer to telescope over the electrodes. I

Instead of having the bare ends electrodes bent over in the same direction, they may be bent over in opposite directions, as shown in Fig. 4, and if desired, the'insulating sleeves may be fused together, as indicated at 25.

Stillgreaterl current carrying capacity may be obtained by giving the downwardly extending endsof the electrodes I6 and I1 an upward bend, as indicated at 26 (see Fig. 5)..

Ii a mercury to mercury contact is desired,

the lupper ends of the insulating -sleeves Il may be spread apart and provided with cups 21 (Fig. 6), the edges of which are protected by annular ceramic lips 28 which are interlocked with the glass insulating sleeves. v The adjacent sides oi' the cups 21 may be fused together, as indicated at '29 (Fig. 7) in order to give the switch structure greater mechanical strength. A ceramic lip 36 may be provided as before. f

In Fig. 8, a modication'is shown in which the insulating sleeve I4 surrounding one ofthe elec. trodes (for example electrode II) is provided with a mercury cup"3I,-the edges of which are protected by a ceramic lip 32, and the other electrode has its insulating sleeve I4 extending only slightly above the low mercury level. Thus, when the displacer 2| is lowered, causing the mercury level to rise, the bared end 33' of the electrodeI I2 (Fig. 8) is rst placedv in contact with the mercury ll and then the circuit is iinally made over the edge of the lip 32 by a mercury to mercury` contact. Upon allowing the displacer to rise, the circuit is broken as soon las the mercury -level falls below the top of the cup 3| `with itsv ceramic lip and the subsequent falling away of the mercury below the top of the insulating sleeve around the electrode I2 has no eect except to place the mercury at zero potential.

' What we clainiz- (1 1.1A mercury switch of the class described comprisinga vertical switch envelope, a mercury ll, a pair of elec-trodes oi opposite polarity project-` ing through the fill, means for sluiting the mercury level toV bridge the electrodes with mercury and hence close the circuit through the -elecof tile two cucinas trode extending above the low level oi.' the iill and exposing a portion of the electrode for contact with the mercury when the mercury is at its high level. i

2. A mercury switch comprising a switch envelope, a mercury illl, a pair of electrodesl of opposite polarity projecting upwardly through the i111, a displacer for shifting the. mercury level to bridge the electrodes with mercury and hence `close the circuit through the electrodes, and an insulating sleeve on each electrode insulating the electrodes from the mercury fill when the switch. is in open circuit position and exposing a portion of the electrode for contact with the mercury vwhen the mercury is at its high level.

3. A mercuryV switch of the class described comprising a switch envelope, a mercury ll, a

- pair of electrodes of opposite polarity sealed throughthe base of the envelope and projecting 'upwardly through the iill, means for shifting the mercurylevel to bridge the electrodes with mercury and hence close the circuit through-the electrodes,v and-means fon insulating both electrodes from the llv when the mercury level is at its `lowest position within the envelope and exposing a portion of each electrode for contact with the mercury when the mercury is at its high level.-

4. A mercury switch of the class described com-v prising a stationary switch envelope, a mercury iill. a pair of spaced 'electrodes ofv opposite 4polar-v ity in the envelope projecting through at least a portion of the mercury ll, and adapted to be bridged by the mercury ll under predetermined v conditions to close the circuit through the electrodes, and meanslforinsulating both electrodes from the till when the switch is in open circuit position and exposing yportions of both'electrodes for contact with the mercury` when the switch is. in its closed circuit position. Y

5. In a mercury switch, a vertical switch envelope, a mercury ll, a displacer for shifting the mercury level and spaced electrodes of opposite* polarity projecting upwardly through the mer-.- cury, said electrodes havingv insulating sleeves extending above the low mercury level but short of the ,ends o f the electrodes.

6. In 'a mercury switch, a vertical envelopeof non-conducting material, a mercury iill, a pair. of electrodes projecting upwardly through the iilll and insulated from the mercuryto a point above the normal level of the mercury. and means i'or bridging the exposed ends of the electrodes with mercury, saidmeans including a mag-r netically responsive displacer.

7*. A mercury switch of the class described comprising`a vertical switch envelope, a mercury ill,

a pair oi electrodes of opposite polarity projecting. 'l

upwardly through the ll, means for shifting the mercury level to bridge the electrodes withmercury and hence close the circuitthrough the electrodes, and an insulating sleeve. on each electrode l I extending above the low level of the illl and exi posing a portion or the electrode for contact with. the' mercury when the mercury is at its high level, a least one of said electrodes-comprising a condu ting `element having an end portion projeeting from its sleeve and turned down to project below the upper end of said sleeve.

8. A mercury switch of the v class described coni-v prising va vertical switch envelope. a mercury n ll,

a pair o'i' electrodes of opposite polarity projecting upwardly through the ll. means for, shiitin'gvthe mercury level to bridge the electrodes with niercury and hence close the circuit through the monaca with themercury when the mercury'ls at its high level, each of said electrodes comprising a conducting element having an end portion projecting from its sleeve and turned over and down in parallel planes oblique to vthe vertical plane through the pair oi' sleeves. l

9. A mercury switch of the class described comprising a vertical switch envelope, a mercury fill, a pair of electrodes of opposite polarity projecting upwardly through the illl, means for shifting the mercury level to bridge the electrodes with mercury and hence close the circuit through the electrodes, and an insulating sleeve on each electrode extending above the low level of the illl and exposing a portion of the electrode for contact with.

the mercury when the mercury is at its high level, each of said electrodes comprising a conducting element having an end portion projecting from its sleeve and turned over and down on opposite Asides oi' said sleeves in parallel' planes substantially normal to the vertical plane through the pair of sleeves. .C

10. A mercury-switch o! the class described comprising a vertical switch envelope, a mercury nil, a pair of electrodes of opposite polarity projecting upwardly through the illl, means for shifting the mercury level to` bridge the electrodes with mercury and hence close the circuit through the electrodes, and an insulating sleeve on each electrode extending above the low level of the fill and exposing a portion of the electrode for contact with the mercury when the mercury is at its high level, said insulating sleeves being joined together and constituting eil'ectively integral parts of a unitary element.

1l. A mercury switch of the class described comprising a vertical switch envelope, a mercury i111, a pair of electrodes of opposite polarity projecting upwardly through the fill, means for shifting the mercury level to bridge the electrodes, and an insulating sleeve on each electrode extending above the low level of the fill and exposing a portion of the electrode for contact with the mercury when the mercury is at its high level, the sleeve of at least one of said electrodes terminating at its upper end in a cup surrounding the end of the electrode and adapted to contain a quantity of mercury.

l2. A mercury switch of the cime described comprising a vertical switch envelope, a rnercury iill, a pair of electrodes of opposite polarity 'projecting upwardly through the fill, means for shifting the mercury level to bridge the electrodes with mercury and hence close the circuit through the electrodes, and an insulating sleeve ori each. electrode extending above the low level of the till and exposing a portion .of the electrode for' contact with the mercury when the mercury is at its high level, the sleeve of one of said elec-` trodes terminating at its upper end in a cup surrounding the end of the electrode and adapted to contain a quantity of mercury, and the sleeve of the other of said electrodes terminating below the level of said quantity of mercury and exposing its electrode for direct contact with the mercury fill when said i'lil is at its high level.

UNO c. HEDIN; CARL H. LARsoN. 

